Majma al-Zawaid 2013 — Spitting outside the mosque

Abd al-Rahman bin Yazid says: We were with Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him). He intended to spit, and there was no one on his right, yet he did not like to spit to his right, even though he was not praying at the time.
Al-Tabarani recorded it in al-Mu'jam al-Kabir, and its narrators are thiqat (trustworthy).